Shidou Itsuka faces greater peril than ever due to his continued involvement with Ratatoskr. He has already sealed 10 Spirits, and Isaac Westcott, leader of Deus Ex Machina Industries, has finally decided to kill Shidou and plunder the Spirits' powers for himself. To achieve his goal, Isaac declares an all-out war against Ratatoskr, forcing the organization to exhaust its resources to ensure Shidou's survival. Despite being severely outnumbered and outmatched, a glimmer of hope exists in the form of the Spirit of Time, Kurumi Tokisaki. Shidou must seal and acquire Kurumi's power to travel to the past and confront the Spirit of Origin—the catalyst that started it all.

With the ensemble contest behind them, the members of the Kitauji High School concert band now aim to win a gold medal at the national competition. For third-year club president Kumiko Oumae and her friends, it is their last chance before graduation. Filled with anticipation and anxiety, Kumiko worries if she can successfully lead the band. Amid her struggles, Kumiko encounters transfer student Mayu Kuroe. From her gentle demeanor to her talented euphonium skills, Mayu was a member of the Seira Girls' School concert band—a regular at nationals. While Mayu is friendly, Kumiko cannot help but have an indescribable feeling from their meeting. As new members arrive and plans are set in motion, the club, with an insatiable hunger for a gold medal, learns what it truly takes to propel themselves to reach the national level.

Haruka Kiyomine and Kei Kaname were once recognized as the most formidable pitcher-catcher duo in middle school baseball. Known as the "General," Kaname paired his expert strategies with Kiyomine's explosive pitches, crushing the dreams of many starry-eyed players who hoped to one day make it to the big leagues. High school freshman Tarou Yamada is one such former player. Having given up on competing, he enrolls in Kotesashi High School—a completely average public school with no baseball team to speak of—where he discovers that his new classmates are the legendary pair who once destroyed his dreams. Adding to this shocking revelation, he learns that amnesia has reduced the once level-headed General to a vulgar class clown. Having lost all interest in baseball, Kaname dragged a disappointed Kiyomine to Kotesashi simply because the school was close to where they live. As Kotesashi forms a fledgling baseball club, Yamada meets other players he once admired who also left baseball behind. While they might be unwilling now, Yamada believes that if he can convince such talented athletes to start playing again, it might be possible to achieve their dreams and win the national championship—as long as they can put up with Kaname's incessant joking.

Featuring stories from the manga not adapted in the main anime.